The store owner and his female employee (who was shot)...
No I'd rather they not get in a shootout at all, but the police didn't shoot first, nor did they disable the vehicle in that location, nor did they force/lead the vehicle to that area... The criminals drove themselves into a corner and decided to go out guns blazing rather than surrender, what came of that is entirely on them, not the police.
The moment the criminals opened fire those people were already at risk. Abstaining from taking cover behind nearby cars would have not only not prevented those people from being in danger (they still would have been in just as much danger), it would have put the police in the direct line of fire. Are you suggesting that when criminals start shooting at police in a crowded area, the police should just stand in the open and essentially commit suicide, lest they endanger people by having the audacity to value their own lives?
If anything you are giving ample reason why they are justified in lighting the truck up, they needed to end the threat as soon as possible to protect the people in the area and themselves.